insu-03747452
https://insu.hal.science/insu-03747452
arxiv:1705.02475
doi:10.1007/s11207-017-1103-6
[INSU] INSU - Institut National des Sciences de l'Univers
[CNRS] CNRS - Centre national de la recherche scientifique
[IAP] Institut d'Astrophysique de Paris
[SORBONNE-UNIVERSITE] Sorbonne Université
[SU-INF-2018] SORBONNE université <2018
[SU-SCIENCES] Faculté des Sciences de Sorbonne Université
[SU-TI] Sorbonne Université - Texte Intégral
[ALLIANCE-SU] Alliance Sorbonne Université
The Na i and Sr ii Resonance Lines in Solar Prominences
Stellmacher, G.
Wiehr, E.
[SDU] Sciences of the Universe [physics]
ART
Prominences
models
Spectral line
broadening
Astrophysics - Solar and Stellar Astrophysics
We estimate the electron density, n<SUB>e</SUB>, and its spatial variation in quiescent prominences from the observed emission ratio of the resonance lines Na i 5890 Å (D<SUB>2</SUB>) and Sr ii 4078 Å. For a bright prominence (τ_{α}≈25) we obtain a mean n<SUB>e</SUB>≈2×10^{10} cm^{-3}; for a faint one (τ _{α }≈4) n<SUB>e</SUB>≈4×10^{10} cm^{-3} on two consecutive days with moderate internal fluctuation and no systematic variation with height above the solar limb. The thermal and non-thermal contributions to the line broadening, T_{kin} and V_{nth}, required to deduce n<SUB>e</SUB> from the emission ratio Na i/Sr ii cannot be unambiguously determined from observed widths of lines from atoms of different mass. The reduced widths, Δλ<SUB>D</SUB>/λ<SUB>0</SUB>, of Sr ii 4078 Å show an excess over those from Na D<SUB>2</SUB> and Hδ 4101 Å, assuming the same T_{kin} and V_{nth}. We attribute this excess broadening to higher non-thermal broadening induced by interaction of ions with the prominence magnetic field. This is suggested by the finding of higher macro-shifts of Sr ii 4078 Å as compared to those from Na D<SUB>2</SUB>.
2017
en
SOLAR PHYSICS